Thanks a lot for this hint! You saved my macbook, when I failed to unscrew the fan because of one completely destroyed screw. Thanks to your comment I skipped steps 7-16 and went straight to replacing the magsafe board without problems. The spudger and some 3D imagination and done,

The steps from 7 up to 16, and then 19 and 20 are not necessary. It looks like Apple intentionally designed the shape in the corner around the magsafe connector, so that it can be replaced without disconnecting and unmounting the main board. Also, the placement of the two screws mounting the magsafe board confirms that - they are easily available. This is true at least for the 2009 model, which I've successfully repaired.

So you can skip the risky steps of disconnecting of all the main board connectors and go straight to unscrewing the magsafe connector. Then, having the spudger and some 3D imagination, you can remove the magsafe board with some 3D rotations. Same for mounting the new magsafe.

I've found out that crucial simplification only because I failed to unscrew the fan (broken a screw completely, while following this guide step by step). Then I found a comment from user grze under step 6, which saved my macbook by confirming, that 7 to 16 can be skipped.